Wow. [Jim Smith] of Grass Roots Engineering has just put the finishing touches on his entirely 3D printed kayak. And it floats.
The individual parts were printed on [Jim's] massive home-made 3D printer, which is loosely based off a RepRap — except that its maximum build volume is a whopping 403 x 403 x 322.7mm.
The kayak itself is made of 28 printed sections, and to hold it all together, he has installed brass threaded thermoplastic inserts, which then allow the pieces to be bolted together. Silicone caulking is applied before assembly to ensure a watertight seal.
It was originally based off of a Siskiwit Bay kayak by [Bryan Hansel] but [Jim] has heavily modified it to suit 3D printing. It was printed at a layer height of 0.65mm to reduce print time, which still ended up being over 1000 hours! He even optimized the design to improve performance based on his own height and weight.